Title: The Scheme for Igneous Rock Identification
1The Scheme for Igneous Rock Identification
2A Brief Tour
3Crystal size
Grain size
Description
4Igneous rocks have Intergrown Crystals
5Intergrown
6Intergrown
7Intergrown
8Not Intergrown
9Where it was formed
Outside the volcano Extrusive
Inside the Earth Intrusive
10Bubbles?
Yes Vesicular
11Bubbles?
NoNon-vesicular
12Color
Neither Light nor Dark
Very Light
NotVery Light
Very Dark
Not Very Dark
Light
Dark
Darkest
Lightest
13Density
Very Light
Medium Density
Light
Dense
Very Dense
14Finding The Minerals
Unless you have other information, work in the
middle of the rocks box.
Identify the rock.
15This is the amount of Potassium Feldspar in the
rock.
16This is the amount of Quartz in the rock.
17This is the amount of Plagioclase Feldspar in the
rock.
18Use tick marks on a scrap paper to measure the
percentage.
Potassium Feldspar 25
Quartz 40
19Practice
Name a light-colored, glassy rock with no bubbles.
20Name a coarse-grained, dense rock.
21Name a dark colored , dense rock that can be
intrusive or extrusive